This invention relates to a method of installing a plurality of coated steel belts as tension members for elevator systems.
Conventional traction elevator systems include a passenger car, a counterweight, two or more wire cables interconnecting the passenger car and the counterweight, a traction sheave to move the cables and a machine to move the traction sheave. Although this design has proven reliable and cost effective for many years, the wire cables employed in such a system have limited service lives. This limitation is the result of several factors. For example, to enhance friction forces between the cable and the sheave, the wrap angle of the cable is either increased or another possibility is to undercut grooves in the sheave. Both techniques subject the cable to increased wear and/or increased rope pressure. Another limitation associated with traditional steel cables is the need to produce cables of a sufficient diameter to comply with elevator safety codes. The imposed cable diameters require larger sheave diameters, which in turn, require greater torque from the machine used to drive the system.
The greater applied torque combined with pressure imposed by the sheave, subjects conventional elevator cables to great stress, which in turn shortens the service life as a tension member. Engineers under the direction of Otis Elevator, designed an elevator tension member that effectively minimized the various stress forces on the member so as to produce a more durable tension member with a longer service life than conventional cables. To accomplish this goal, the tension member consists of a plurality of individual load carrying cords encased within a common layer of coating that separates the individual cords while at the same time defining an engagement surface for the traction sheave. The coating layer is formed from a polyurethane material extruded onto and through the plurality of cords. The resulting tension member is relatively flat. The flattening out of the tension member minimizes the thickness and maximizes the width of the tension member without sacrificing cross-sectional area or load carrying capacity. As a result, stronger more flexible xe2x80x9cbelt-likexe2x80x9d elevator tension members are produced. Details relating to the manufacture of coated steel elevator tension belts are disclosed in commonly owned U.S. patent application Ser. No. 09/031,108 now U.S. Pat. No. 6,401,871 the contents of which is herein incorporated in its entirety by inference. This novel tension member shall hereinafter be referred to as a xe2x80x9ccoated steel belt.xe2x80x9d This design distributes the pressure more uniformly throughout the tension member, thus reducing the maximum pressure applied to the tension member as compared to a conventional cable having a similar load capacity. Furthermore, the effective member diameter of the sheave is minimized which in turn reduces the magnitude of the torque needed to drive the sheave which in turn increases the rotational speed. Coated steel belts permit the use of less costly, more compact high speed motors as the driving mechanism of the elevator system.
The traction sheave and one surface of the coated steel belt are complimentary contoured to provide traction and to guide the engagement between the coated steel belt and the sheave. Conventional elevator cables, having no such traction enhancing contouring, need only be individually fed down the elevator shaft for installation. It was discovered that attempts to install the novel coated steel belts using traditional elevator cable installation methods were time consuming and resulted in damage to the belts. Because of its contoured surface, diligent attention was required to ensure proper installation of the coated steel belts so that the contoured surface of the belts came in contact with the surface of the sheave. The coated steel belts have a tendency to twist when fed individually down the elevator shaft. This twisting can damage the belt. Therefore, there exists a need for a new and improved method of installing coated steel belts as tension members in elevator systems without causing twisting of the coated steel belts during installation.
In view of the forgoing disadvantages inherent in the conventional methods present in the prior art, the present invention provides an improved method of installing coated steel belt tension members in elevator systems.
It was a goal of the present inventor to provide a low cost easy-to-use storage and feeding device which can readily accommodate and dispense a plurality of belts in an exceptionally rapid manner. Due to the spatial limitations associated with elevator systems, the dispensers need to be easily lifted and transported to the elevator machine room or hoistway.
To accomplish this goal, the present inventor devised a portable coated steel belt dispensing device capable of portioning out a plurality of belts. A continuous coated steel belt is rolled from end to end and is retained in place in a box-like structure. A hollow core is passed through two opposing holes in the side walls of the dispenser through the center of the steel belt roll. The core is cradled by the side walls of the dispenser. The walls of the box-like structure can be made from corrugated plastic or cardboard. The core acts as an axle rotatably supporting the coat steel belt rolls. A plurality of steel belt rolls can be rotatably supported by a single core so long as the center of each roll have similar dimensions.
The wall of the dispensing device located at the free end of the steel belt roll has a elliptical perforation that can be punched out by the technician during installation to retrieve the free ends of the rolls. When a dispensing force is exerted on the free end of the coated steel belt roll which is generally greater than the relative weight of the roll, the roll begins to systematically unravel, dispensing the belt out of the aforementioned perforated slit. The dispensing force is created by the technician pulling on the free end of the steel belt roll causing the roll to rotate on the core.
To position a plurality of steel belts in the dispenser, the technician deposits the desired number of steel belt rolls of equivalent lengths side-by-side vertically in the dispenser. The rolls should be positioned in the dispenser so that hollow centers of the rolls are aligned so that the core can be passed easily through each roll. The cylindrical perforations formed in the side walls of the dispenser are removed forming a hole in each side panel and the cylindrical axel is passed through one side panel hole, therethrough the centers of the steel belt rolls and then partially through the opposing hole in the opposite wall of the dispenser so that the ends of the axel are rotatably supported by the two side walls. If assembled correctly, the plurality of steel belt rolls should be rotatably supported by said axel.
To install a plurality steel belt in an elevator system in accordance with this invention, the technician first removes the elliptical perforation formed in the forward panel of the dispenser to retrieve the terminal ends of the individual belts. The technician unrolls equal amounts of the coated steel belts and aligns the edges. The terminal ends of the coated steel belts are then secured between two steel plates bolted together so as to apply or compression force on the ends of the steel belts sufficient to retain the belts, tightly. The clamped steel belts are then fed throughout the path of the elevator system and positioned in place.
The method described herein offers many advantages over the prior art method of installing elevator support means. First, it offers an efficient way to install coated steel belts. Second, a plurality of elevator steel belts can be installed at the same time, saving installation time, thus decreasing costs. Finally, the described method effectively eliminates twisting of the belts that can cause damage and properly aligns the coated steel belts with the sheaves.